Conventionally, a dual-clutch device is known, in which two clutches capable of connecting and disconnecting a driving power transmission from a driving source, such as an engine, by means of a pressure of a hydraulic oil are provided therein and also a driving power transmission path from the driving source to a transmission is switched between transmission lines, each of which is formed via one of the clutches.
Engaging and disengaging of each of the clutches of such a dual-clutch device are controlled by adjusting an amount or pressure of the hydraulic oil to be supplied to each of the clutches.
In addition, a dual-clutch device is also known, in which a hydraulic oil is supplied to a space around clutch plates of each of clutches in order to discharge a frictional heat generated by the clutch plates of each of the clutches.
In such a dual-clutch device, if the hydraulic oil is supplied to the space around the clutch plates, there is an advantage that heat generated in the clutch plates can be discharged, but there is also a disadvantage that a drag torque is generated in the clutch plates by the hydraulic oil, thereby causing deterioration of fuel consumption.
For example, for an automatic transmission, a technique is known, in which a flow rate of a lubricating oil is corrected on the basis of a generated drag torque, thereby adjusting the drag torque (e.g., see Patent Document 1).